Temporary bridges planned for collapsed I-5

MOUNT VERNON, Wash. - Plans are underway to construct a pair of temporary steel bridges across the Skagit River in Mount Vernon where a highway span collapsed into the water Thursday evening.

Planners hope to have the temporary structures in place within three weeks. Repair work would then begin on the damaged bridge, with a goal of finishing that work by fall. A two-week closure during a transition to a new permanent bridge is expected in September.

“The plan minimizes the closure time and keeps clear access to popular Skagit County retail business and destinations including the Anacortes ferry terminal,” Gov. Jay Inslee said in a statement.

The temporary four-lane bridge will carry Interstate 5 traffic over the Skagit River at a reduced speed and capacity. The bridge will consist of two 24-foot wide structures to replace the collapsed section of the bridge. These structures will be pre-built and trucked to the site to allow for accelerated installation, according to Inslee’s office.

The federal government is expected to cover 90 percent of the cost of the temporary bridge and the replacement.

Once debris has been removed, further underwater structural examinations will determine if additional repairs are needed before installing the temporary span, according to Inslee’s office.

Crews plan to start work on the permanent bridge when the temporary span is put in place, and also put temporary piers into the river to support a platform adjacent to the collapsed span where the new section will be built.

Once complete, the temporary span will be removed and the new permanent span will be moved into place. WSDOT hopes to have the permanent bridge open to traffic in early fall.

The initial estimate for the total cost of a permanent fix is $15 million.

“We ask for everyone’s patience as we transition from emergency operations to long-term repair,” WSDOT Transportation Secretary Lynn Peterson said in a statement.

Reduced speeds during the interim fix mean traffic backups will continue to be a challenge, both locally and on I-5. The detours will remain in place to provide drivers with travel options. That stretch of I-5 handles about 71,000 vehicles each day and is the only north-south interstate in Washington.